The purpose of this study is to characterize the specificity of interaction of salivary glycoproteins with oral Streptococci. Glycoproteins which will be studied include highly purified mucin, lactoferrin, and secretory IgA. Streptococci to be studied include representative strains of the three serotypes of Streptococcus sanguis as described by Rosen (Infect. and Immun. 13, 1144, 1976). Studies will be aimed at determining what portion of each salivary glycoprotein (ligand) is responsible for specific interactions with the representative strains of S. sanguis. The salivary ligands will then be utilized to isolate the bacterial surface component involved in the glycoprotein-bacterial interaction. Isolation will be performed using affinity chromatography techniques. Purified surface components will then be characterized with respect to their chemical and physical properties. The results obtained will aid in clarifying the mechanisms by which oral Streptococci interact with oral surfaces and provide an insight into the selective nature of bacterial adherence in non-immune reactions.